A vehicular alternator (alternating current generator) is required to be small-sized and capable of supplying required power in low-speed rotations or high-speed rotations. The number of turns of a stator winding of a vehicular alternator is changed to meet such needs. However, when only the number of turns (T) of the stator windings is changed in a conventional vehicular alternator 1 having a Y-connected stator winding 23 and a rectifier device 5 as shown in FIG. 12, the output characteristics of the alternator changes as shown in FIG. 13. In FIG. 13, respective characteristic curves A, B and C show the output characteristic of the vehicular alternator when the number of turns (T) of the stator winding 23 is set to 3, 4 and 5. As the number of turns is changed from one integer number of turns to another integer number of turns, the output characteristic is stepwisely changed. Therefore, a desired output characteristic cannot be achieved.